Washington (CNN) -- Actress Daryl Hannah was arrested Tuesday during a sit-in in front of the White House protesting a pipeline expansion project that would significantly increase the amount of oil the United States imports from Canada's controversial Alberta oil sands.

The "Splash" actress was among more than 100 people arrested at the demonstration, according to the group that organized the protest.

"We stand here today to just say no to slavery, to just say no to tar, sands, oil, and no to the Keystone pipeline," Hannah said before her arrest.

A representative for the actress was unaware of the arrest when contacted by CNN Tuesday afternoon.

The State Department is set to issue what could be a final ruling to allow a massive new pipeline expansion from central Alberta to the Gulf of Mexico. A decision is expected by the end of the year, State Department spokeswoman Heide Fulton said at a briefing last month.

Known as Keystone, the project is an expansion of an existing pipeline that now terminates in Oklahoma. Stretching over 1,600 miles -- twice the length of the Trans-Alaska system -- the new pipeline would be one of the biggest in the country.

Canada's oil sands have drawn numerous critics who say the way the oil is extracted harms the environment.